Recovery of metals from their ores



Patented June 21, 1932 UNITED STATES PATENT OFFICE LESLIE G. J" EN NESS', F BROOKLYN, NEW YORK, ASSIG-NOR TO INTER/METAL CORPORA- TION, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE RECOVERY OF METALS FROM THEIR ORES No Drawing.

In my copending application Serial No. 365L340 filed May 18, 1929, I have described and claimed a general method of selectively reducing and volatilizing various metals contained in an ore and thus separately recovering eachmetal as a chloride. The method there described and claimed comprises the steps of selective reduction and simultaneous chlorination andvolatilization in the presence of sulphur chlorides and chlorine at regulated temperatures. By this method each metal in an ore is separately recovered as a chloride at a given predetermined temperature which is distinct from the tempera.- ture at which each other metal is recovered.

I have also, in my copending application Serial No. 38 L809 filed-August 9, 1929, described a modification of the process above mentioned which is especially adapted for the treatment of certain ores. It is pointed out in this latter copending application, that if certain ores are given an ignition treatment previously to their treatment with sul phur chlorides and chlorine, themetallic constituents of the ore are rendered more resistant to volatilization under treatment by the sulphur chlorides and chlorine. The ignition treatment, moreover, causes a spread between the reduction and volatilization temperatures of the metallic constituents wider than is found in the natural unignited ore.

It is an object of the present invention to provide a'process which avails itself of an ignition treatment similar to that of my said copending application, Serial No. 384,809,

and a subsequent reduction and chlorination similar to that described and claimed in my said copending application, Serial No. 364,340, with this difference, however, that, instead of volatilizing the metallic compounds and separately recovering them in the manner shown in said copending applica tions, the process of the present invention proceeds after reduction and chlorination at temperatures too low to volatilize any substantial amount of the chlorides so formed. It is a further object to obtain by the method herein described and claimed compounds of various metals that are soluble in aqueous solutions and which can accordingly be ob- Application filed December 20, 1929. Serial No. 415,622.

tained from the ore so treated by leaching methods.

I have discovered that in the case of many ores, there is another very great and curious difference between the response of ignited ores to the action of sulphur chlorides and chlorine and the response of these ores when not ignited. In some cases ignition seems to effect an actual reversal between thestarting points of distillation of two given metals. I have found for example that, when Wolframite is ignited at a temperature of approximately 700 C. for a period of two to three hours both the tungsten and iron in the ore are made more refractory to subsequent volatilization by sulphur chlorides and chlorine, but that the volatilization is repressed more in the case of tungsten than of iron. The ore, furthermore, increases in weight on ignition.

I will illustrate the process by describing its application to one ore, namely, wolframite, although the process is not limited to that ore only.

The ore is first ground. It is not, however, essential that the particles should be very fine as the present process gives excellent results with ore ground as coarse as about 100 mesh. This ore is then ignited in a furnace for fromtwo to three hours at about 700 C.

It should here be pointed o'utfthat this ignition is not essential to the success of the present process. It seems, however, to cause a cracked or porous condition of the ore particles, thus providing more surface on which the gases may act. But whether this explanation be the correct one or not, I have found that with ore previously ignited in this manner, halfv as much more soluble tungsten compounds can be obtained than in the case of unignited ore. I have also found, as hereinabove pointed out that the ignition seems to impart a greater resistance to volatilization under the sulphur chloride and chlorine n treatment.

After this ignition. treatment,z sulphur chlorides and chlorine are passed over the ore while a temperaturefof about 200 C. is

maintained in the furnace. As, very little volatilization of the tungsten occurs until a temperature of over 200 C. is attained, substantially all the tungsten remains in the ore in a reduced and chloridized form.

At this temperature, indeed, both iron and tungsten are thus reduced and remain in the residue. I have also discovered that between 180 C. and 200 0., a compound of tungsten is formed which is soluble in aqueous solutions blltWlllChflS readily-volatilized at temm peratures in the neighborhood of 230 C. and higher. I consider. it v of advantage, therefore, in the present process to maintain the temperature at about-200 C. or below during the sulphur chloride and chlorine 1 treatment because volatilization, which is not e'sirable in the present process, becomes appreciable at about 205 C.

At 200 C. substantially all the tungsten is easily converted to the soluble form. Some small portion of the tungsten is,'indeed, volatilized,but-this'can be condensed by maintaining a lower temperature in the exit end It willbe observed that the process of this invention aims at the production of soluble .compoundsof the metals,by utilizing sulphur chlorides and chlorine at temperatures below the points of rapid volatilization of their chlorides. It is probable that some of these .resulting soluble compounds are chlorides other than the normal chlorides, and, indeed,-they.seem to be such.

I have, produced soluble compounds of vanadiumand titanium by treating the ignited ores with sulphur chlorides and chlorme.

When ore has-thus been reduced and chlorinated, it may be easily recovered by leaching. Sodium carbonate may be used as a leach forming a sodium tungstate solution, the iron remaining insoluble. From this solution tungstic acid is precipitated by adding it to hot hydrochloric acid solution. Then this tungstic acid :is heated at 700 C. a very high grade tungstic oxide is obtained.

I prefer, however, notto leach with sodium carbonate because of the very great ,50 .difliculty of removing the alkali from the product obtained. By using ammonium hyv drate (NI-L0H) as a leach, ammonium tungstate is taken .up in solution. Iron and other constituents are left in the gangue. By evaporation, a paratungstate is crystallized out and a very pure tungstic oxide isobtained either by heating or by treating with nitricfand hydrochloric acids followed'by ignition.

.the sodium carbonate will be easilyappreciated from the resulting product. In pracmg with ammonia, however, all alkali metals are avoided.

The process of'lthe present patent, indeed, affords a convenientmethod of decomposing iron tungstate without efiect upon the remainder of thegangue. It also renders tungsten soluble in alkaline solutions and by converting the tungsten to a readily soluble con- 'dition, makes'it possible to use ammonia solutions forthe leach, so that no alkali metals need come in contact with the tungsten.

.Finally an exceedingly pure grade of tung-. stic acid can be prepared by a single leach I and precipitation. of the furnace. It will then pass outwith I the remainder of the ore and be recovered 5 by leaching as hereinafter described.

What I claim is 1. The process ofrecovering tungsten from the ore which consists in igniting the finely Idivided ore at a'temperature of about 700 0., treating said ignited ore with sulphur chlorides and chlorine at about 200, (3., and then leaching the ore so treated;

2. The process of recoveringtungsten from the ore which consists in igniting the finely divided ore at atemperature of about 700 (1, treating said ignited ore with'sulphur chloridesand chlorine at about 200. (1., and then leaching the ore so treated with ammonium hydroxide.

3. The process of recovering tungsten from 131160116 which consists in igniting the finely divided ore at atemperature .of about .7 00 G., treating said ignited ore with sulphur chlorides and chlorine at about 200 C., and: then leaching the ore so treated witlra leach free from alkali metal compounds.

tQThe process of recovering tungsten from the ore which comprises treating the ore with sulphur chlorides and chlorineat a temperature below the rapid volatilization temperature 230 C. of the thus formed chlo- :ridized tungsten product; and then suitably leaching said product out of said ore.

'5. The process of recovering tungsten from the'ore which comprises treating the ore with sulphur chlorides and chlorine at a temperature below the rapid volatilizati'on temperature 230 C. of the-:chloridized tungsten product; and thenleachingthe ore so treated with ammonium hydroxide.

In testimony whereof, I havehereunto set my hand this 18th day .of December, 1929.

The advantage of the ammonia leach over I r j LESLIE G. JENNESS.

v tically all present methods of production of .tungsticacid, analkali metal mustcome into contact with the tungsten. 'Wh ere sodium 

